This project uses a variety of epidemiologic techniques in conjunction with collaborating laboratories to investigate the relative role of viruses and genetics in human virus-associated tumors. Emphasis is placed on the intensive study of tumors occurring in unusual situations suggestive of an environmental etiologic factor. Evaluation of the immune response to specific candidate oncogenic agents and a search for chromosomal or other genetic markers are performed in an attempt to determine whether genetics affects the response to ubiquitous viruses in the appearance of malignancy. Among the findings in these studies are the following: Evidence for an oncogene was found in the leukemic cells of a woman with familial cancer in the course of studies of the entire family; evidence for pre-existing inability to produce IgG antibody following virus infection was apparent prior to the development of Hodgkin's disease in another patient; an antigen cross-reacting with gp52 of the mouse mammary tumor virus was found to be more prevalent in tumors from breast cancer patients in Tunisia than in those from patients in the United States; nasopharyngeal carcinoma (NPC) was found to have previously unrecognized coastal pattern in the United States; analysis of NPC patients identified by the Surveillance, Epidemiology and End Results Program indicated that environmental factors in Hawaii contribute to a higher incidence of NPC in that state than in any other. HTLV was found to have a higher frequency in Ghana than in other parts of Africa, the United States, South Africa, Egypt and Singapore.